When you're multiplying fractions, you have to multiply the numerators together (2 & 7) and then the denominators (21 & 40). 2x7=14 and 21x40= 840. Therefore, the fraction becomes 14/840. To simplify it, you can divide it by 2, and this gives you 7/420. Both 7 and 420 are both divisible by 7, this then gives you 1/60. Therefore, 2/21x 7/40 in the simplest form is 1/60 Hope this helps :)