Y=x+7
5x+2y=7 in solving systems of equations by substitution

x = -1 and y = 6

Step-by-step explanation:

y = x + 7

5x + 2y = 7

y - x = 7(1)

2y + 5x = 7(2)

multiply equation (1) by 2

2y - 2x = 14

2y + 5x = 7

subtract equation (2) from (1)

2y - 2x = 14

- 2y + 5x = 7

0 -7x = 7

-7x = 7

divide both sides by 7

-7x = 7

7 7

-x = 1 multiply through by minus sign

x = -1

substitute x = -1 into equation (1)

y - x = 7

y - (-1) = 7

y + 1 = 7

y = 7 - 1

y = 6

answer:

12.5 yards/ 37.5 feet

step-by-step explanation:

0.4ft (the shadow of the yardstick) x 12.5= 5ft (the shadow of the tree) so the tree is 12.5 yards tall since the height of 12.5 yardsticks will cast the same shadow. 12.5 yards is also 37.5 feet.