(7×3/4)cm+(4×2/3)cm+(Xcm)= 18cm

Answer 1

7 × 3 / 4 cm + 4 × 2 / 3 cm + X cm = 18 cm

You don't have to write a unit of measure in the equation.

The whole calculation is done with numbers. and the unit of measurement is written at the end of the calculation.

( 7 × 3 ) / 4 + ( 4 × 2 ) / 3 + x = 18

21 / 4 + 8 / 3 + x = 18
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Remark:

Least common multiple of 4 and 3 is 12
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21 × 3 / ( 4 × 3 ) + 8 × 4 / ( 3 × 4 ) + x = 18

63 / 12 + 32 / 12 + x = 18

95 / 12 + x = 18

95 / 12 + x = 18 × 12 / 12

95 / 12 + x = 216 / 12

Subtract 95 / 12 to both sides

95 / 12 + x - 95 / 12 = 216 / 12 - 95 / 12

x = 121 / 12

x = 121 / 12 cm