how many multiples of 7 are there between 21 and 343 , inclusive ?
"7 * 3 = 21 7 * 49 = 343 total multiples = ( 49 - 3 ) + 1 = 47 include 21 and 343 = 47 answer is b"
add(divide(subtract(343, 21), 7), const_1)