Question

решить математику номер 668 и 669

Answer 1

$668.\\\\\\1){1\over4}x=80\\x=80\times 4\\x=320\\\\2){1\over10}x=10\\x=10\times10\\x=100\\\\3){1\over2}x=30\\x=30\times2\\x=60\\\\4){1\over5}x=20\\x=20\times5\\x=100\\\\5){3\over4}x=60\\x=60\times{4\over3}\\x=80\\\\6){3\over5}x=90\\x=90\times{5\over3}\\x=150\\\\7){2\over3}x=10\\x=10\times {3\over2}\\x=15\\\\8){5\over6}x=50\\x=50\times{6\over5}\\x=60\\\\9){3\over7}x=30\\x=30\times{7\over3}\\x=70$

$669.\\\\\\1){3\over4}\times8=6\\\\2){5\over8}\times12=7.5\\\\3){2\over5}\times10=4\\\\4){3\over10}\times5=1.5\\\\5){5\over6}\times8=6{2\over3}\\\\6){3\over4}\times20=15$