Final answer:
To combine like terms, multiply each term inside the parenthesis by the outside factor; hence, 20(-1.5r + 0.75) simplifies to -30r + 15, which is option b.
Step-by-step explanation:
The task at hand is to combine like terms in the given expression 20(-1.5r + 0.75) to find an equivalent expression.
Combining like terms involves simplifying the expression by multiplying each term inside the parenthesis by the factor outside, which in this case is 20.
Performing this operation, we multiply -1.5r by 20 to get -30r, and multiply 0.75 by 20 to get +15.
The resulting expression is -30r + 15, neatly combined and simplified.
So, the answer to the given problem is b) -30r + 15.