Given:
Three numbers in an AP, all positive.
Sum is 21.
Sum of squares is 155.
Common difference is positive.
We do not know what x and y stand for. Will just solve for the three numbers in the AP.
Let m=middle number, then since sum=21, m=21/3=7
Let d=common difference.
Sum of squares
(7-d)^2+7^2+(7+d)^2=155
Expand left-hand side
3*7^2-2d^2=155
d^2=(155-147)/2=4
d=+2 or -2
=+2 (common difference is positive)
Therefore the three numbers of the AP are
{7-2,7,7+2}, or
{5,7,9}
Answer:

Step-by-step explanation:
there are 4 quarters to 1 hour
3 1/6 x 4 =
19/6 * 4 = 76/6 = 12 4/6, reduces to 12 2/3 km per hour
Answer:
y = x -7
Step-by-step explanation:
2x - 2y = 14
The slope intercept form is
y = mx+b where m is the slope and b is the y intercept
Subtract 2x from each side
2x - 2y -2x = -2x+14
-2y = -2x+14
Divide each side by -2
-2y/-2 = -2x/-2 +14/-2
y = x -7
The slope is 1 and the y intercept is -7
Tada, Its on the Image. Hoped I helped :)