X+42=83-27; x:9=600:100; 28:x=400:100; x-(25+19)=36
×+42=83-27 ×+42=56 ×=56-42 ×=14 ×÷9=600÷100 ×÷9=6 ×=9×6 ×=54 28÷×=400÷100 28÷×=4 ×=28÷4 ×=12 ×-(25+19)=36 ×-44=36 ×=36+44 ×=80