floating$-$point that consists of $4$ binary $($i$.$e$.,$ base$-2)$

digits for the mantissa and $3$ binary digits for the exponent $($plus sign bits$).$

a $=(\mathrm{.}1011)2\backslash$times $2^1$

b$=(\mathrm{.}1100)2\backslash$times $2^0$

what is $($a$+$b$),($a$-$b$),($a$-$b$)^8,($a$+($b$/2)),($a$+($b$/4)).$ Is each answer exact, rounded, overflow, or underflow and why.