You're told that various holdings are 1/5, 1/10, 2/7, 1/5, 1/10 and you want the remainder. Remembering that 1/5 is the same as 2/10, 3/15, 4/20 and so forth, we want to express the holdings all as multiples of the same part (acommon denominator). The denominators (bottom lines) are 5,10 and 7, so a common multiple is 70: that is, any number of 5ths, 7ths or 10ths can be expressed as 70ths. (70 is the smallest number we can use, so its theleast common denominator.) Since 70 = 14 times 5, 1/5 = 14/70: 1/10 = 7/70, 2/7 = 20/70. The various holdings are now 14, 7, 20, 14 and 7 in units of 1/70, so total 62/70. Hence the remaining holding is 70-62 = 8 in units of 1/70, that is, 8/70 = 4/35.

If the total holding is X (try to find the quantity you're being asked for and give it a letter), then the cash holding is 4X/35. You're told this = 7000. Solve this equation for X.