Question

A vegetable store sold 3 tons of vegetables less on the first day than on the second, and on the third day it sold 5/9 of the amount sold in the first two days. How many vegetables was the store selling every day if it sold altogether 98 tons of vegetables for the three days?

Answer 1

Let
x---------> quantity (ton) of vegetables sold the first day
y---------> quantity (ton)  of vegetables sold the second day
z---------> quantity (ton) of vegetables sold the third day

we know that
x=y-3---------> equation 1
z=(5/9)*(x+y)------> equation 2
x+y+z=98-----> equation 3
substitute equation 2 in equation 3
x+y+[(5/9)*(x+y)]=98----> multiply by 9----> 9x+9y+5x+5y=882
14x+14y=882-----> equation 4

to resolve the equations system formed by
x=y-3
14x+14y=882

using a graph tool
see the attached figure
the solution is
x=30
y=33
x+y+z=98----> z=98-(x+y)----> z=98-63---> 35

the answer is
vegetables sold the first day----> 30 ton
vegetables sold the second day----> 33 ton
vegetables sold the third day------> 35 ton

Answer 2

Answer:
amount sold on first day = 30 tons
amount sold on second day = 33 tons
amount sold in third day = 35 tons

Explanation:
Assume that the amount of vegetables sold on the second day is x.
We are given that:
Amount of vegetables sold on the first day is 3 tons less that sold on the second day.
This means that:
amount sold on first day = x - 3 
Amount of vegetables sold on the third day is 5/9 the amount sold on the first two days.
This means that:
amount sold on third day = (5/9) (x + x - 3)
amount sold on third day = $\frac{10}{9} x - \frac{5}{3}$

Now, we know that:
Total amount sold is 98 tons.
This means that:
98 = x - 3 + x + $\frac{10}{9} x - \frac{5}{3}$

Now, we will solve for x as follows:
98 = $\frac{28}{9} x - \frac{14}{3}$

882 = 28x - 42
882 + 42 = 28x
924 = 28x
x = 924/28
x = 33 tons

This means that:
amount sold on first day = x - 3 = 33 - 3 = 30 tons
amount sold on second day = x = 33 tons
amount sold on third day = $\frac{10}{9} x - \frac{5}{3}$ = $\frac{10}{9} (33) - \frac{5}{3}$ = 35 tons

Hope this helps :)