First, the number given in g(x) is 4, so look at the graph. You need to find that number that makes one of the statements true.
The true statement is at 4≤x<8, because 4≤4, and 4<8, so replace the x on equation 0.5x+10 with 4.
0.5(4)+10
0.5 × 4 = 2
2+10 = 12
So, the value for g(4) is 12.