Excel for DNA Sequencing analysis - how can I find a string of text within a large string?

A TGCTGTGTTGTGGATGAATTAGATGCAG
B GCAGATCTCAAAAGAAGGAGTACTCCGAA

1 TGCTGTGTTGTGGATGAATTAGATGCAGATCTCAAAAGAAGGAGTACTCCGAA
2 TGCTGTGTTGTGGATGAATTAGATCTCAAAAGAAGGAGTACTCCGAA
3 TGCTGTGTTGTGGATGAATTAGTCAAAAGAAGGAGTACTCCGAA
4 TGCTGTGTTGTGGATCTCAAAAGAAGGAGTACTCCGAA
5 TGCTGTGTTGTGGATGAATTAGATGCATCTCAAAAGAAGGAGTACTCCGAA
6 TGCTGTGTTGTGGATGAAGGAGTACTCCGAA
7 TGCTGTGTTGTGGATGAATTAGAAGGAGTACTCCGAA
8 TGCTGTGTTGTGGATGATCTCAAAAGAAGGAGTACTCCGAA
9 TGCTGTGTTGTGGATGAA


I want to find how much of Text String A is in Text String 1 starting from Left to Right. Then I want to find out how much of Text String B is in Text String 1 from right to left. So on and so forth for 1-9. Any ideas?