Follow PEMDAS
first simplify the parenthesis
10 + 5 = 15
6 - 5 = 1
9(15)/1
multiply 9 and 15 together
9(15) = 135
135/1 = 135
B. 135 is your answer
hope this helps
Answer: 7.4a+b
1. distribute
=5a+(2.4)(a)+(2.4)(0.5b)+−0.2b
=5a+2.4a+1.2b+−0.2b
2. combine like terms
=5a+2.4a+1.2b+−0.2b
=(5a+2.4a)+(1.2b+−0.2b)
=7.4a+b
Because when you subtract a negative number the signs cancel out and become and addition problems
Commutative property. :)) Its when 2 numbers are multiplied togther and the product is the same regardless of the order of the 2 numbers.