Proportion:
a/b = c/d
where: cross products are equal.
ad = bc
a/b = c/d
a = 4 4/9 = 28/x
b = 9 cross products
c = 28 ad = bc
d = x 4x = 9*28
4x = 252
4x/4 = 252/4
x = 63
4/9 = 28/x
4/9 = 28/63
4/9 is the simplified factor of 28/63.
28 ÷ 7 = 4
63 ÷ 7 = 9
Another solution for this is.
4/9 = 28/x
x is a denominator, we need to eliminate it. To do so, we must make x the numerator. so we multiply both side with x.
4/9 * x/1 = 28/x * x/1
4x/9 = 28
4x/9 * 9/1 = 28 * 9/1 *eliminate the denominator 9 by multiplying both sides with numerator 9.
4x = 252
4x/4 = 252/4
x = 63
