SAT Question 585de39a: Probability And Conditional Probability answer and explanation with Desmos solution

It's given that in Nigeria on September $30$, $2015$, the probability of selecting an MTN subscriber from all Internet subscribers is $0.43$, that there were $p$ million, or $p(1,000,000)$, MTN subscribers, and that there were $97$ million, or $97,000,000$, Internet subscribers. The probability of selecting an MTN subscriber from all Internet subscribers can be found by dividing the number of MTN subscribers by the total number of Internet subscribers. Therefore, the equation $\frac{p(1,000,000)}{97,000,000}=0.43$ can be used to solve for $p$. Dividing $1,000,000$ from the numerator and denominator of the expression on the left-hand side yields $\frac{p}{97}=0.43$. Multiplying both sides of this equation by $97$ yields $p=0.43\times 97=41.71$, which, to the nearest integer, is $42$.