Answer:
Step-by-step: i hate khan academy so much
x=5
Step-by-step explanation
3.18x+2.6+0.9x+x=28
3.18x+0.9x+x+2.6=28
5.08x+2.6=28
5.08x+2.6-2.6=28-2.6
5.08x=25.4
hope it helps