15p là dở rồi:>

a.15-(x-7)=\(\left(-5\right)^2\)
x-7=(-10)
x=(-3)
b.-5x-(-3)=13
-5x=10
x=(-2)
c.(x-3)-8=(-7)
(x-3)=1
x=4

 

Anh bạn à....đang thi hả:>

a. hstl=10.12=120
b.y=\(\dfrac{a}{x}\)
c.y=\(\dfrac{120}{-4}=\left(-30\right)\)
y=\(\dfrac{120}{12}=10\)
y=\(\dfrac{120}{6}=20\)