Calculate.

a) [[$ 11 \displaystyle\frac {1} {7} + 5 \displaystyle\frac {3} {7} = $]]

b) [[$ 7 \displaystyle\frac {1} {4} + 3 \displaystyle\frac {1} {3} = $]]

c) [[$ 8 - 2 \displaystyle\frac {3} {4} = $]]

d) [[$ 6 \displaystyle\frac {3} {5} - 1 \displaystyle\frac {1} {4} = $]]