Question

Solve the following system of equations by substation.

5y = 7x + 22
x = -6y + 17

A. (2,-1)
B. (5,3)
C. (-1,3)
D. (-1,4)

Answer 1

C. (-1, 3)

Explanation:

Label the 2 equations:

5y= 7x +22 -----(1)

x= -6y +17 -----(2)

Substitute (2) into (1):

5y= 7(-6y +17) +22

5y= -42y +119 +22 (Expand bracket)

5y= -42y +141 (Simplify)

42y +5y= 141 (+42y on both sides)

47y= 141

y= 141 ÷47 (÷47 on both sides)

y= 3

Substitute y= 3 into (2):

x= -6(3) +17

x= -18 +17

x= -1

Thus, the solution is (-1, 3).