b + 7.5 = 4.8
-7.5 -7.5
-----------------------
b = -2.7
Hope this helps!!!!!
You can also check your answer by doing replacing the number with the variable ( don't just write the anwser just because you know it, since its pre algebra you have to do it algebraically like above)
-2.7 + 7.5 = 4.8
Hope it helps!