Answer:
0.13x+(70000-x)0.05=6000
We move all terms to the left:
0.13x+(70000-x)0.05-(6000)=0
We add all the numbers together, and all the variables
0.13x+(-1x+70000)0.05-6000=0
We multiply parentheses
0.13x-0.05x+3500-6000=0
We add all the numbers together, and all the variables
0.08x-2500=0
We move all terms containing x to the left, all other terms to the right
0.08x=2500
x=2500/0.08
x=31250
Explanation: