Part (a):
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6 : 9 = x : 72
![(6)/(9) = (x)/(72)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/9ird8374sm85uw3adpucvlql9jug7fp5es.png)
By using cross multiplication
∴ 9 x = 6 * 72
∴ 9 x = 432
∴ x = 432/9 = 48============================================
Part (b):
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8 : 3 = 40 : x
![(8)/(3) = (40)/(x)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/tmtdu5njso5c5a7z2vhqi491rt5pgca2oa.png)
By using cross multiplication
∴ 8x = 3 * 40
∴ 8x = 120
∴ x = 120/8 = 15============================================
Part (c):
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x : 55 = 3 : 5
![(x)/(55) = (3)/(5)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/lveefu6j5wv26bizlzls9isqpq0tbkmekx.png)
By using cross multiplication
∴ 5 x = 3 * 55
∴ 5 x = 165
∴ x = 165/5 = 33============================================
Part (d):
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33 : x = 11 : 5
![(33)/(x) = (11)/(5)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/8ebtmsbax3mxzskf857ze6htasbwamvtv1.png)
By using cross multiplication
∴ 11 x = 5 * 33
∴ 11 x = 165
∴ x = 165/11= 15============================================