Factorise means to put into brackets and solve means to find values of x that make the equation true.We need to find two numbers that multiply to make 15 and add together to make -8. They both need to be negative numbers to get negative 8 and positive 15 (as a negative multiplied by a negative gives a positive). So, it will be (x-5)(x-3)=0.Now, set each bracket to equal 0. x-5=0 and x-3=0Solve to get x equals by adding 5 and 3 to both sides.Therefore, x=5 and x=3.