Question

7x + 3y = 30
-2x + 3y = 3

A. (3, 5)
B. (6, 3)
C. (3, 3)
D. (6, 5)

Answer 1

7x + 3y = 30 ----> (-1)
-2x + 3y = 3
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-7x - 3y = -30 (result of multiplying by -1)
-2x + 3y = 3
--------------add
-9x = - 27 (divide both sides by -9)
x = 3
now sub 3 in for x in either equation to find y
7x + 3y = 30
7(3) + 3y = 30
21 + 3y = 30
3y = 30 - 21
3y = 9
y = 3

check..
-2x + 3y = 3
-2(3) + 3(3) = 3
-6 + 9 = 3
3 = 3 (correct)

x = 3 and y = 3 or (3,3)