Answer:
$10
Step-by-step explanation:
x is her weekly allowance.
She spent half her allowance and has ½x remaining.
She earned $7, and now has $12.
12 = ½x+7
x = 10
What's 18 × 15 ?
Hint : 270
let the integers be x and y
x+y=-20
y=-20-x
xy=99
x(-20-x)=99
-20x-x²=99
x²+20x+99=0
x²+11x+9x+99=0
x(x+11)+9(x+11)=0
(x+11)(x+9)=0
x=-11,-9
when x=-11
-11+y=-20
y=-20=11=-9
when x=-9
-9+y=-20
y=-20+9=-11
so integers are -11,-9
