Answer:
The unknown variable d is, 25
Step-by-step explanation:
Proportion states that two ratios or fractions are equal.
Solve for d:
[tex]\frac{15}{d} = \frac{24}{40}[/tex]
By cross multiply we have;
[tex]600 = 24d[/tex]
Divide both sides by 24 we have;
[tex]\frac{600}{24} = d[/tex]
Simplify:
25 = d
or
d = 25
therefore, the unknown variable d is, 25.