Both problems are proportions, so cross multiply in each problem to get rid of the fractions.
41. [tex] \dfrac{9}{x} = \dfrac{12}{21} [/tex]
Reduce the fraction in the right side.
[tex] \dfrac{9}{x} = \dfrac{4}{7} [/tex]
Cross multiply.
[tex] 4x = 9 \times 7 [/tex]
[tex] 4x = 63 [/tex]
[tex] x = \dfrac{63}{4} [/tex]
[tex] x = 15.75 [/tex]
43. [tex] \dfrac{5}{2} = \dfrac{10}{x - 2} [/tex]
Cross multiply.
[tex] 5(x - 2) = 2 \times 10 [/tex]
[tex] 5x - 10 = 20 [/tex]
[tex] 5x = 30 [/tex]
[tex] x = 6 [/tex]
