Answer:
B
Step-by-step explanation:
Since x varies directly as y, the ratio of x to y remains the same. Let the value of x when y=4 be a. Then we have
[tex]\dfrac {7 \frac12} {10} = \dfrac a4[/tex]
We can cross multiply to get that
[tex]10a = 30, \text{so } \boxed{a=3}[/tex]
