so first, we need to find a common denominator, make the numbers below the line equal to each other
to do this, we multiply the denominator AND numerator of 4/10 so you can get the equivilent fraction with a denominator of 100
4*10=40
10*10=100
4/10=40/100
now we add the two fractions together and we get
38/100+40/100=
78/100 of a meter