Problem: 3x+5y=81 9x+7y=189
what is the intercept of x and y
1) 3x + 5y = 81
2) 9x + 7y = 189
Multiply equation 1 by 3.
3(3x + 5y) = 81 * 3
3) 9x + 15y = 243
Subtract equation 2 from equation 3.
9x + 15y = 243
-(9x + 7y = 189)
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8y = 54
8y = 54
8y/8 = 54/8
y = 6.75
3x + 5y = 81
3x + 5(6.75) = 81
3x + 33.75 = 81
3x + 33.75 - 33.75 = 81 - 33.75
3x = 47.25
3x/3 = 47.25/3
x = 15.75
Check.
9x + 7y = 189
9(15.75) + 7(6.75) = 189
141.75 + 47.25 = 189
189 = 189
Answer: x = 15.75, y = 6.75
Point (15.75, 6.75)