ANSWER:

STEP-BY-STEP EXPLANATION:
We have the following expression:

In order to operate, we must first break the parentheses and then group similar terms, like this:
Do you have a picture? i can help if you have one
Answer:
x=15
Step-by-step explanation:
(10*9)/6=10*x/10
90/6=x
15=x
Answer:
18.90
Step-by-step explanation:
3x12=36
36-15=21
21 x 0.9
84 because 36 x 2 =72 and then 1/3 of 36 is 12 and 12+72=84