`a) 541 + ( 218 - x) = 735`
`=> 218 - x = 735 - 541 = 694`
`=> x = 218 - 694 = -476`
`b) 96 - 3( x + 1) = 42`
`=> 3(x + 1) = 96 - 42 = 54`
`=> x + 1 = 54 : 3 = 18`
`=> x = 17`
`c) ( x - 47) - 115 = 0`
`=> x - 47 = 0 + 115 = 115`
`=> x = 115 + 47 = 162`
`d) ( x - 36) : 18 = 12`
`=> x - 36 = 216`
`=> x = 216 + 36 = 252`
`e) ( 7.x - 15) : 3 = 2`
`=> 7x - 15 = 6`
`=> 7x = 6 + 15 = 21`
`=> x = 21 : 7 = 3`
`f) 44 + 7.x = 100`
`=> 7x = 56`
`=> x = 56 : 7 = 8`
`g) 88 - 3.( 7 + x) = 68`
`=> 3.( 7 +x) = 88 - 64 = 24`
`=> 7 + x = 24 : 3 = 8`
`=> x = 8 - 7 = 1`
`h) 315 - ( 5x + 80) = 155`
`=> 5x + 80 = 315 - 55 = 260`
`=> 5x = 260 - 80 = 180`
`=> x = 180 : 5 = 36`