48a+25a+7=443; 4(9+7х)+21=393

48а+25а+7=44348а+25а=443-7(48+25)а=43673а=436а=436:73а=5,9

48а+25а+7=443; 73а=443-7; 73а=436; а=436:73; а=5,974(9+7х)+21=393; 36+28х=393-21; 28х=372-36; 28х=336; х=336:28; х=12