4. 47 − 2, 47 − 20, 54 − 3, 54 + 30, 76 − 20, 76 + 20, 68 + 8 + 2, 45 + 6 + 4

№ 4: \(47-2=45\), \(47-20=27\), \(54-3=51\), \(54+30=84\), \(76-20=56\), \(76+20=96\), \(68+8+2=78\), \(45+6+4=55\).