Let the missing number be x .
Then :-
[tex] \frac{3}{8} = \frac{15}{x} [/tex]
[tex] 3 \times x = 8 \times 15[/tex]
[tex]3x = 120[/tex]
[tex]x = \frac{120}{3} [/tex]
[tex]x = 40[/tex]
The missing number is 40 .
Let us check it by doing cross multiplication :-
[tex]3 \times 40 = 15 \times 8[/tex]
[tex]120 = 120[/tex]
Hence proved the missing number is 40 .
[tex]therefore \: , \frac{3}{8} = \frac{15}{40} [/tex]
