2 1/7 ÷ ( 1,5а)= 5 / 14 ÷ 0,8
1/7÷1.5a=5/14÷0,8 1/7 * 0.8=5/14 *1.5a 1/7 *4/5=5/14*1,5a 4/35=5/14*3/2a 4/35=15/28a 16/75=a
спасибо