a. AP=2/3·AM <=> 2/3·AM=24 <=> AM=36
PM=1/3·AM <=> PM=12
BP+2/3·BN <=> 2/3·BN=30 <=> BN=45
PN=1/3·BN <=> PN=1/3·45 <=> PN=15
b. PM=1/3·AM <=> √6=1/3·AM <=> AM=3√6
AP=2/3·AM <=> AP=2/3·3√6 <=> AP=2√6
PN=1/3·BN <=> √7=1/3·BN <=> BN=3√7
BP=2/3·BN <=> BP=2/3·3√7 <=> BP=2√7