Let's do subtraction by first starting with the ones place and then the tenths place of the subtrahend. 45-4=41; 44, 43, 42, 41 41-.5= 40.5; 40.9, 40.8, 40.7, 40.6, 40.5 45-4.5=40.5 We can check by using addition. 40.5+4.5= 44+1= 45
A variable is a quantity that may change within the context of a mathematical problem or experiment. ... The letters x, y, and z are common generic symbols used for variables. Sometimes, we will choose a letter that reminds us of the quantity it represents, such as t for time, v for voltage, or b for bacteria.