Suppose that the $1-$year interest rate is currently $8\%$ on British pound and $6\%$ on US dollar. $($a$)$ If the current ER is $$1\mathrm{.}25/,$ what would be the expected ER one year from now? $($b$)$ If the expected spot rate is to decline to $$1\mathrm{.}15/,$ how much the US interest rate would have changed?