Double the first equation: 4x+14y=-2 and subtract the second: 17y=17, so y=1. 2x=-7y-1=-7-1=-8, so x=-8/2=-4.
The answer is x=-4 and y=1.
The answer is (3,0). Hope this helps!(:
Answer:
Sue must score 94 on the final test to earn a B.
Step-by-step explanation:
There are five tests in total.
Sue's average on the first four tests is 84.
If after the final test, she scores X, she will have a B on average of five tests.
We have the following equation:
86 = (4 × 84 + X)/5
<=> X = 5 × 86 - 4 × 84
=> X = 94
"Will is twice as old as Jill."
Jill's age . . . . . J
Will's age . . . . 2J .
"Three years ago . . .
Jill's age then . . . . . J - 3
Will's age then . . . . 2J - 3
". . . Jill's age then was 2/5 of Will's age then."
J - 3 = (2/5) (2J - 3)
Multiply
each side by 5 : 5J - 15 = 2 (2J - 3)
Divide
each side by 2 : 2.5 J - 7.5 = 2J - 3
Subtract 2J
from each side: 0.5 J - 7.5 = -3
Add 7.5
to each side: 0.5 J = 4.5
Multiply
each side by 2 : J = 9
Jill is 9 y.o. now.
Will is 18 y.o. now.
