Make r the subject of the formula x = (3r - 4)/5

Factorise fully 12x^2-20x+3

The point P has coordinates (3,4). The Point Q has the coordinates (a,b). A line perpendicular to PQ is given by the equation 3x+2y=7. Find an expression for b in terms of a.

How would I solve this set of simultaneous equations using the elimination method?

There are 10 balls in a bag. The balls are the same apart from their colour. Of the 10 balls, 3 are black, 5 white, 2 red. What is the probability of picking a white ball from the bag.