Răspuns:
15. 948÷7=135 r 4
(135×7)+4=948
897÷5=179 r 4
(179×5)+4=879
562÷6=93,6
(93×6)+6=562
16.8×(30+20)
=8×50=400
24×32+24×18-24×10
=(32+18-10)×24
=(50-10)×24
=40×24=960
17. 1028-28×15=1028-420
=608
800-(112÷4+9×4)÷8+70×45=800-(28+36)÷8+70×45
=800-64÷8+70×45
=800-8+70×45
=800-8+3150
=292+3150
=3442
[(147÷7-5)+3×4]÷4-2012×0=0
18.
a)1932+×=2301
×=2301-1932=369
b)×-748-3654=97
×=97+3654+748
×=3751+748=4499
c)957+3185-×=1634
×=1634+3185-957
×=4819-957=3862
d)837-253-×=194
×=194+253+837
×=447+837=1284
19.
a)235.402+a=236.702
a=236.702-235.402=1300
b)53.201-a=23.141
a=53.201-23.141=30.060
c)a+17.132=25.432=8312
d)a-25.754=14.123
a=25.754+14.123=11.631
e)48.045÷a=3203
a=48.045÷3203=15
f)a÷24.573=137
a=24.573×137=3.366.501
g)73.121×a=1.754.904
a=1.754.904÷73.121=24
h)a×4312=90.552
a=90.552÷4312=21
