book Maths Puzzle Numerical Ability

Could you please help me solve these problems..

x+7y=21

y=1/4x+2

y=-2/3x+4

Read Solution (Total 0)

book Other Question

Show that the points(5,7), (3,9) and (6,8) are the vertices of a right triangle.

can use distance formula or slope.
use the properties of logarithms to condense the following expression:
1) 3 ln x + 2 ln (x+1)