Because the graph is a "V" shape, the X value is an absolute value which is written as |x|.
Then the point of the V is on Y = 3, so we know we need to add 3 to to the end of the equation.
The last part of the equation we need to find is the slope.
Using the given points (0,3) and (1,5)
The slope would be (5-3) / (1-0) = 2/1 = 2
The equation becomes y = 2|x| + 3