Question

1. 10r - 5r + 3r - 8r

Explanation:

Step1: Combine like terms stepwise

$10r - 5r + 3r - 8r = (10r - 5r) + 3r - 8r$

Step2: Calculate first pair of terms

$= 5r + 3r - 8r$

Step3: Add next two terms

$= 8r - 8r$

Step4: Subtract final terms

$= 0r$

Answer:

$0$