a)15+17-14+78-25=32+64-25=32+41=73
b)66+34-25-15+30-24=100-25+15-24=75+15-24=90-24=66
c)2X6:4X8:2-4=12:4x4=3X4=12
d)5X4X5:10X5:5=20X5:10X1=100:10=10
e)8X9-64:8X3+54:6X4=72-8x3+9x4=72-24+36=48+36=84
f)55:5x7-63:7X3+44:4:1=11X7-9x3+11=77-27+11=50+11=61
