Question 1

Let x be the amount of money invested with the 10% interest.

Equation would be

Invested in 10% = $575, invested in 7% - $825

Question 2

Let x be the amount of shirts the shopkeeper owns

Let y be the amount of ties the shopkeeper owns

Hence,

- eqn 1

- eqn 2

eqn 2 - eqn 1 =