Question

What is the value of s in the equation 3r = 10 + 5s, when r = 10

Answer 1

3r= 10+ 5s

When r= 10:
3*10= 10+ 5s
⇒ 5s= 3*10 -10
⇒ 5s= 30-10
⇒ 5s= 20
⇒ s= 20/5
⇒ s= 4

The final answer is s=4~

Answer 2

just substitute the value of r in the equation;

3r = 10 + 5s

3(10) = 10 + 5s

30 = 10 + 5s (next combine like terms)

30 - 10 = 10 -10 + 5s (subtracted 10 on both sides)

20 = 5s

20 ÷ 5 = s (did the inverse operation)

4 = s or s = 4