Question 93823
1/3=4/12
3/4=9/12 now add these & set them=13
4x/12+9x/12=13
13x/12=13 now cross multiply
13x=12*13 now divide both sides by 13
x=12 answer
proof
1*12/3+3*12/4=13
4+36/4=13
4+9=13
13=13