Question

被减数与减数的和是4.2,被减数与差的和是4.8,被减数是多少

Answer 1

A-B=C,A=B+C

A+B=4.2 (1)

A+C=4.8 (2)

(2)-(1),得C-B=0.6,

C=B+0.6 (3)

A+B=4.2,

B+B+C=4.2(4)

将(3)带入(4),

得3B+0.6=4.2,B=1.2

C=1.8

A=3

原式为3-1.2=1.8