Answer:
![\boxed {\boxed {\sf 15}}](https://img.qammunity.org/2022/formulas/mathematics/college/rs23x2jtjiv0mmgkgu863wmayenth4q3xn.png)
Explanation:
Distance is calculated using this formula:
![d=\sqrt {(x_2-x_2)^2+(y_2-y_1)^2](https://img.qammunity.org/2022/formulas/mathematics/college/65wmu5ezah4hfokm8ch6e2o90h5i667d02.png)
where (x₁, y₁) and (x₂, y₂) are the points. We are given (-3,8) and (-3,7). Therefore;
![x_1= -3 \\y_1= 8 \\x_2= -3 \\y_2= -7](https://img.qammunity.org/2022/formulas/mathematics/college/ycpcouuoow2adt3y717mykxaldrg7eyzw7.png)
Substitute the values into the formula.
![d= \sqrt {(-3--3)^2+(-7-8)^2](https://img.qammunity.org/2022/formulas/mathematics/college/8i251n21geacuyi98cwn6rueqylo7b89es.png)
Solve inside the parentheses.
- -3 - - 3= -3+3= 0
- -7 - 8 = -15
![d= \sqrt {(0)^2+(-15)^2](https://img.qammunity.org/2022/formulas/mathematics/college/grv4yqhmmltpjuumxp89z4vbwj3sxubccn.png)
Solve the exponents.
- 0²=0*0= 0
- -15²= -15*-15=225
![d=\sqrt {0+225](https://img.qammunity.org/2022/formulas/mathematics/college/fjelb4jfjvx1dyxt7w0meqhs3itj3iinbc.png)
![d=\sqrt {225](https://img.qammunity.org/2022/formulas/mathematics/college/fxsk54tey55x44vr5v6zlqxu05qm6m1nao.png)
![d= \pm 15](https://img.qammunity.org/2022/formulas/mathematics/college/5cccqmlsi75kxo4gdgg2kj0hf4uargbj9c.png)
A negative number for distance doesn't make sense, so the distance must be 15.