Can somebody helP

2x + 1 < 5 solve the following inequality. then place the correct number in the box provided.

The brain volumes (cm cubed) of 50 brains vary from a low of 904 cm cubed to a high of 1488 cm cubed. use the range rule of thumb to estimate the standard deviation s and compare the result to the exact standard deviation of 175.5 cm cubed, assuming the estimate is accurate if it is within 15 cm cubed

If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)