Let x be the number of bolts bought.
Let y be the number of washers bought.
Thus, we have:
0.55x + 0.07y = 2.41 --- (1)
x + y = 7 --- (2)
From (2), we have:
y = 7 - x --- (3)
Substitute (3) into (1), and we will get:
0.55x + 0.07(7 - x) = 2.41
0.55x + 0.49 - 0.07x = 2.41
0.48x = 1.92
x = 1.92 / 0.48
x = 4
Substituting x = 4 into (3), we will get:
y = 7 - 4 = 3
Hence, he bought 4 bolts and 3 washers.