f.1 maths

At the beginning , Alloy A contains 22% of iron ,
so , when there is 2.5kg of Alloy A,
it contains 2.5*22%=0.55kg iron

Alloy B contains 40% of iron ,
thus, when there is 3.5 kg of Alloy B,
it contains 3.5*40%=1.4kg iron

When they are melted and recast ,
the total mass of the alloy is 2.5+3.5=6kg

the total iron in the alloy is 1.4+0.55=1.95kg

the percentage of iron in the formed alloy is 1.95/6*100%=32.5%

I hope it can help you ^^