Solve the following time addition and subtraction problems.

$$5 \text{ hr} + 3 \text{ hr} = 8 \text{ hr}$$

The sum is $\boxed{\text{8 hr}}$.

b) $8 \text{ hr} + 2 \text{ hr}$

$$8 \text{ hr} + 2 \text{ hr} = 10 \text{ hr}$$

The sum is $\boxed{\text{10 hr}}$.

c) $7 \text{ hr} + 4 \text{ hr}$

$$7 \text{ hr} + 4 \text{ hr} = 11 \text{ hr}$$

The sum is $\boxed{\text{11 hr}}$.

d) $9 \text{ hr} + 6 \text{ hr}$

$$9 \text{ hr} + 6 \text{ hr} = 15 \text{ hr}$$

The sum is $\boxed{\text{15 hr}}$.

e) $10 \text{ hr} + 7 \text{ hr}$

$$10 \text{ hr} + 7 \text{ hr} = 17 \text{ hr}$$

The sum is $\boxed{\text{17 hr}}$.

f) $11 \text{ hr} + 8 \text{ hr}$

$$11 \text{ hr} + 8 \text{ hr} = 19 \text{ hr}$$

The sum is $\boxed{\text{19 hr}}$.

g) $1 \text{ hr} + 12 \text{ hr}$

$$1 \text{ hr} + 12 \text{ hr} = 13 \text{ hr}$$

The sum is $\boxed{\text{13 hr}}$.

h) $5 \text{ hr} + 5 \text{ hr}$

$$5 \text{ hr} + 5 \text{ hr} = 10 \text{ hr}$$

The sum is $\boxed{\text{10 hr}}$.

2. Write the time vertically and subtract.

a) $9 \text{ hr} - 3 \text{ hr}$

$$9 \text{ hr} - 3 \text{ hr} = 6 \text{ hr}$$

The difference is $\boxed{\text{6 hr}}$.

b) $7 \text{ hr} - 4 \text{ hr}$

$$7 \text{ hr} - 4 \text{ hr} = 3 \text{ hr}$$

The difference is $\boxed{\text{3 hr}}$.

c) $6 \text{ hr} - 5 \text{ hr}$

$$6 \text{ hr} - 5 \text{ hr} = 1 \text{ hr}$$

The difference is $\boxed{\text{1 hr}}$.

d) $10 \text{ hr} - 1 \text{ hr}$

$$10 \text{ hr} - 1 \text{ hr} = 9 \text{ hr}$$

The difference is $\boxed{\text{9 hr}}$.

e) $12 \text{ hr} - 9 \text{ hr}$

$$12 \text{ hr} - 9 \text{ hr} = 3 \text{ hr}$$

The difference is $\boxed{\text{3 hr}}$.

f) $11 \text{ hr} - 5 \text{ hr}$

$$11 \text{ hr} - 5 \text{ hr} = 6 \text{ hr}$$

The difference is $\boxed{\text{6 hr}}$.

g) $8 \text{ hr} - 4 \text{ hr}$

$$8 \text{ hr} - 4 \text{ hr} = 4 \text{ hr}$$

The difference is $\boxed{\text{4 hr}}$.

h) $15 \text{ hr} - 7 \text{ hr}$

$$15 \text{ hr} - 7 \text{ hr} = 8 \text{ hr}$$

The difference is $\boxed{\text{8 hr}}$.