Answer:
s = -7.8
Step-by-step explanation:
from the question 12=10(s+4)+50
first step
open the bracket and evaluate for the value of s
12=10(s+4)+50
12 = 10s + 40 + 50
12 = 10s + 90
collect or combine the like terms
12-90 = 10s
-78 = 10s
divide both side by 10
-78/10 = 10s/10
-7.8 = s
therefor s = -7.8
