Very easy math question

ok so i need

9/7 and 4/5 to have the same denominator

i think i remember that you have to multiply the bottom (5) by 7 and the 7 by 5 what do you do with the top do you multiply the 9 by the 4 and the 4 by the 9 or do you multiply the 9 by the 5 and the four by the 7 ?

Multiply both numerator and denominator with the SAME number because that proportionally=1, and multiplying any number by one does not change its value. You want 35, the LCM of both denominators in the denominator. So, you'd have to multiply both 9 and 7 by 5 and both 4 and 5 by 7.

7 and 5 don't have common factors so 7*5=35

first term is 9/7 and we multiply it by 1
well it is a special 1 where 1=5/5
we picked 5 because this is denominator of other fraction.

9*5/7*5=45/35

the second one is also multiplied by 1 where 1=7/7 because 7 was denominator of other fraction.

4/5 * 7/7 = 4*7/5*7=28/35

done...

9/7 = 45/35 What ever you do to the numerator (top) , you must also do to the denominator(bottom) ( times 5 in this case)

4/5 = 28/35 Again whatever you do to the numerator has to be done to the denominator. (times 7 in this case)

very easy question.
we have to multiply 9/7 by 5/5 and 4/5 by 7/7. because 5/5 equal to 1 and 7/7 equal to 1.

The answer is 73/35