Pretend the m isnt there 4.2 - 1.4 = 7.5 4.2-1.4=2.8 now put the m back
2.8+m=7.5 7.5-2.8=4.7 therefore 4.2 + 4.7 -1.4 = 7.5
or
4.2 + m - 1.4 = 7.5
-4.2 +1.4 = -4.2 +1.4
______________________
0 + m - 0 =4.7


