Need subtracting negative numbers

i don't know why, but i can't seem to understand it.

i understand adding positives, but subtracting positive numbers i can't do it

why is -7- 7 =-14? and not 0? i know its simple, but can someone explain it to me like im 12?

Could answer every question with steps

Guys i really need or i have to stay late up night

Astudent draws two parabolas on graph paper. both parabolas cross the x-axis at (-4, 0) and (6,0). the y-intercept of thefirst parabola is (0, –12). the y-intercept of the second parabola is (0-24). what is the positive difference between the avalues for the two functions that describe the parabolas? write your answer as a decimal rounded to the nearest tenth.