Answer:
r=-40
Step-by-step explanation:
r/-8=5
times -8 on both sides
5 times -8 =-40
r=-40

Substract '-3.4x' at LHS nad the RHS of the above expression.

Add '4' on both LHS and RHs of the above expression.
Answer:
10
Step-by-step explanation:
25% is the same as 0.25 so multiply 40 by 0.25.
7x (2x^2 - 3) is your answer my dude/lady