Answer:
x = 11
Step-by-step explanation:
[tex] \frac{wvu}{wv} = \frac{wg}{wh} \\ \\ \frac{28}{40} = \frac{7}{x = 1} \\ \\ 28(x - 1) = 40 \times 7 \\ \\ 28 \: x - 28 = 280 \\ 28x = 308 \\ x = 11[/tex]