the common denominator is 10 (between 5 and 2)
for each numerator:
we divide the common denominator with the denominator of each fraction and then multiply with the numerator of the fraction
first fraction's numerator:
10 (c.d.) : 5 (denominator) = 2
2 * 2 (numerator) = 4
second one:
10 (c.d.) : 2 (denominator) = 5
5 * 1 (numerator) = 5
The fractions are 4/10 and 5/10