a) 345x=23*255=5865, x=5865/345=17
b) (23*4900)/100=23*49=1127
c) (11*624)/24=11*26=286
d) 31*(x+1)=13*(2x+7), 31x+31=26x+91, 31x-26x=91-31, 5x=60, x=60/5=12
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