1. 2x + 5y = 7
2. 3x + 6y = 3
Multiply Equation 1. by 3 and Equation 2. by 2:
1'. 6x  15y = 21
2'. 6x + 12y = 6
Add Equations 1' and 2' to eliminate x
y(15 + 12) = (21 + 6)
3y = 15
y = 5
Substitute this value of y into either Equation 1 or 2 and solve for x:
1. 2x + 5y = 7 ⇒ 2x + 5(5) = 7
2x = (7  25) = 18
x = 9
Check answer:
Does 3(9) + 6(5) = 3?
Does 27 + 30 = 3?
YES!!
Dec 15

William S.