Final answer:
Amy used 234 more beads on Monday than on Tuesday.
Step-by-step explanation:
To find out how many more beads Amy used on Monday than Tuesday, we need to calculate the number of beads she used on each day. Let's start by representing the total number of beads Amy had originally as 'x'. On Monday, she used 1/4 of the beads, which is (1/4)x = x/4 beads. The number of beads she had left after Monday is (3/4)x. On Tuesday, she used 2/5 of the remaining beads, which is (2/5)(3/4)x = (6/20)x = (3/10)x beads.
To find out how many beads she had after Tuesday, we subtract the beads used on Tuesday from the remaining beads after Monday: (3/4)x - (3/10)x = (6/20)x - (3/10)x = (3/20)x beads. We know that after buying 399 beads, she had the same number of beads as she had initially. Therefore, (3/20)x + 399 = x. We can now solve for x: 399 = (20/20)x - (3/20)x, 399 = (17/20)x, x = (399 * 20) / 17 = 4680 beads.
Now, to find the difference between the beads used on Monday and Tuesday, we calculate: (1/4)x - (3/10)x = (10/40)x - (12/40)x = (10 - 12)/40x = -2/40x = -1/20x. As we have found the value of x to be 4680, we can substitute it into the equation: (-1/20)(4680) = -234 beads.
Therefore, Amy used 234 more beads on Monday than on Tuesday.