The point of the form $(a, -a)$ always lies on the line

For the equation $5x + 3y = 90$,if $x = 12$,then $y = \dots$

Express the following linear equation in the form $ax + by + c = 0$ and indicate the values of $a, b,$ and $c$ in each case: $y = x + 5$.

Write four solutions for the following equation: $2x - 5y = 10$.

The graph of the linear equation $5x - 3y = 20$ intersects the $x$-axis at:

The total cost of a school picnic consists of two parts: a fixed bus fare of ₹ $200$ and the cost of snacks at the rate of ₹ $30$ per student. Representing the total number of students by $x$ and the total cost by $y$,form a linear equation in two variables. If the number of students going on the picnic is $40$,find the total cost.