This link to a video will help
https://youtu.be/k3RwfEvqrB8
Then your amount was reduced to $15 less
<span>Let x = # of rides
Plan A: 10 + 3x
Plan B: 20 + x
if x < 5 rides then plan A is better buy
if x = 5 both plans are the same
if x > 5 then plan B is the best buy
Prove:
x = 6 (rides)
plan A: </span>10 + 3x = 10 + 3(6) = 10+18 = $28
plan B: 20 + x = 20 + 6 = $26
To do this we will divide d amount of dollars by d amount of lbs.
Lets do it:-
16.87 ÷ 3.5 = 4.82
1 lb of trail mix is for $4.82
CHECK OUR WORK:-
4.82 × 3.5 = 16.87
We were RIGHT!!
So, 1 lb of trail mix costs $4.82.
Hope I helped ya!! xD

so, 13 of the 20 tables have 6 chairs each.
that means, the remaining 7 tables, have 4 chairs each.
13 * 6 = 78 chairs total for those 13 tables.
7 * 4 = 28 chairs total for the remaining 7 tables.
78 + 28, that's how many.