Answer:
43
Step-by-step explanation:
So we want the number of pebbles p, when divided into groups of 7 has a remainder of 1 and when dividing by 5 leaves 3 extra.
So what does this mean? well, using division we want to say p - 1 is divisible by 7 and p - 3 is divisible by 5
So what you want to do is either count by 7s, add one to get a new number x then subtract 3 and see if it is divisible by 5, or go the other way and count by 5s, add 3 to get x then subtract 1 and see if it is divisible by 7.
To make it into a formula use (7x +1)-3 or (5x + 3)-7. There may be a formula but I cannot recall it. I am going to use the formula with the 7 though, because it is easier to tell if a number is divisible by 5.
(7(1) +1)-3 = 5 but less than 10 so no
(7(2) +1)-3 = 12
(7(3) +1)-3 = 19
26
33
40 Divisible by 5! so just add the 3 back to get 43 and that is the number of pebbles that fits the description. it is one more than 42 which is divisible by 7
