Can I maintain a 90 average if I just got a 73% on my first test?

[i love you :)]

I really wanna do good. & I wanna atleast a 90 average. When I got my first test this year back today, I gotta 73. What am I supposed to do? Ugh. It's not like I miss out on homework or anything. Its just the test. Can I still maintain a 90 average?