They want to make a profit of $3,000.
Their income is $1.25 per subscription. Then, the total income is 1.25x, being x the number of subscriptions.
Their expenses are fixed (that is, they do not depend on the number of subscriptions) and are $100 and $150, a total of $250.
Then, we can write the equation for the profit P in function of the number of subscriptions as:
If profit needs to be larger than $3000, we can write:
And solve:
They need at least 2600 subscriptions to make $3000 in proft.