Question 69036
Four times s is 4s.

Therefore, the sum of 4 times s and r is (4s + r)

The parentheses are used to make it clear that you are dealing with the sum.  You are asked to multiply the sum by t.

t times this sum is t*(4s+r)   

This is the algebraic expression you were asked to find.

Evaluate the expression by substituting 2 for r, 5 for s, and 0.5 for t to get:

                    0.5 * (4*5 + 2)

Inside the parentheses first do the multiplication 4 times 5.  Then add 2 to that answer.  4*5 is 20 and adding 2 results in 22.  Substitute 22 into the expression in place of (4*5 + 2) to get:

                     0.5 * 22

And 0.5 * 22 = 11

The answer to the evaluation for the given values of r, s, and t is 11